Lathem Dukane 24A715 - Manual (Page 44)

Wiring Secondary Clocks
The next several pages contain wiring diagrams and theory of operation for the secondary
clocks. These are listed in numerical order according to type code number.
Note:
All circuits should be fused or protected by a circuit breaker (10A maximum).
The 24A715 and 24A715M master clocks are factory-equipped to operate analog clocks
on the CLK1 output (relays 7 and 8), and CLK2 output (relays 5 and 6).
—IMPORTANT—
If the master clock will operate Dukane digital clocks, the digital clocks MUST
be operated from the CLK1 output (relays 7 and 8), and relay 7 MUST be
replaced with a solid-state relay to support the digital clocks. To obtain the
required solid-state relay, order Model 438-860 from Dukane.
TYPE 01—Synchronous Wired
For a list of Type 01 clocks, see the chart on the first page of this appendix.
In normal operation, the synchronous secondary clocks are operated from 24Vac or
120Vac, using the 60Hz power source to maintain clock accuracy. An error in the time
displayed by the secondary clock can be introduced by a power failure. The master clock
will correct the time displayed on the secondary clock using two synchronization meth-
ods: minute hand correction and absolute correction.
Minute hand correction takes place once every hour, even if there is no error in the dis-
played time. The master clock sends an eight-second pulse to the secondary clock’s
correction circuit, starting at the 57th minute and 54th second, and lasting until the 58th
minute and 2nd second of every hour. This causes the secondary clock to advance its
hands until the minute hand is correct. The hour hand will still be in error at the end of
this cycle if the error at the beginning of the cycle was in excess of one hour.
If the secondary clocks are more than one hour off, the master clock initiates an absolute
correction by sending a six-second pulse, beginning at 5:58:02 (both AM and PM) and
ending at 5:58:08. This correction cycle takes a long time to completely update the sec-
ondary clocks. Depending on how far off the secondary clocks are, the correction cycle
can take many hours to complete. The correction cycle does not run continuously, so it
may be difficult to establish whether or not the secondary clocks have completed their
correction activities.
B-2 24A715/24A715M Master Clock Installation Manual